In large scale integrated and greatly miniaturized semiconductor components, the problem that occurs to an intensified extent after said components have been mounted on printed circuits (printed circuit boards) is that in the event of temperature fluctuations, on account of the different thermal expansion coefficients of the materials involved, strong mechanical stresses occur within the component and between the component and the printed circuit board. FIG. 5 shows a customary design of such a miniaturized semiconductor module. The semiconductor component 1 is connected to the printed circuit board 2 by its electrical contacts 5. The semiconductor chip 3 in turn is connected to the interposer 12 by means of electrical contacts 14, the semiconductor chip being bonded to the interposer for the purpose of mechanical stabilization by means of an underfiller 13. The semiconductor chip 3 is furthermore encapsulated with an encapsulation 15. The interposer 12 as carrier is often also completely encapsulated as well.
Owing to temperature fluctuations or variations, mechanical stresses occur in the known component forms on account of the different thermal expansion coefficients of the different materials. FIG. 6 illustrates this in greater detail. The semiconductor chip 3 has a lower thermal expansion coefficient α than the interposer 12, which is produced from a different material. On account of the different expansion of the semiconductor chip and of the interposer, a strong mechanical stress 16 is transmitted via the underfiller 13, which is necessary for mechanical fixing and stabilization, and generated in the interposer 12. In order that a connection fracture of the electrical contacts 14 does not arise here, the thermal expansion coefficient of the interposer must already be adapted to the semiconductor chip. However, printed circuit boards 2 that are usually used have a thermal expansion coefficient that is greatly different from semiconductor chips. Therefore, the interposer 12, which is already under mechanical stress, exerts a strong mechanical stress 17 on the printed circuit board 2 via the electrical contacts 5 strained by said interposer. In the extreme case, this strong mechanical strain can lead to a deformation of the printed circuit board, which, particularly in the case of double-sided populations of printed circuit boards, may lead to the fracture of electrical contacts 5 and thus to the destruction of the electronic apparatus. If the deformation does not immediately lead to fracture in the choice of many instances of strain and strain relief it will then lead to fatigue of the material of the electrical contacts 5, which then again ultimately leads to the fracture thereof and limits the service life. Moreover, the high degree of different expansion, and thus the mechanical strain, of the semiconductor component in itself, that is to say on the one hand between semiconductor chip and interposer, and a semiconductor chip and encapsulation—in which a strain 18 is again induced—on the other hand, leads to fatigue of the electrical contacts 14, as a result of which the electrical contacts within the semiconductor components 1 may also be destroyed.
Direct placement of a semiconductor chip onto a printed circuit board only by means of bumps, in order to prevent mechanical stresses or transmissions thereof from interposed layers, does not achieve the goal either since a stable mechanical connection between the semiconductor chip and the printed circuit board cannot be produced by this means. Moreover, adhesive bonding of a chip by means of bumps with an underfiller, for example in the form of a resist, would here only carry the direct strains from the semiconductor chip to the printed circuit board. This would again result in deformation of the printed circuit board, with the abovementioned difficulties. In particular, in the case of printed circuit boards populated on both sides, it would lead to a destruction of circuits situated on one side of a printed circuit board or of the electrical contacts of said circuits.
In order that electronic circuits with a sufficiently long life can nevertheless be produced, complicated and thus expensive housing constructions are necessary for semiconductor components.